The device for measuring oxidation-reduction potential (ORP) is also known as “redox sensor”. “Redox” is a composite word of “reduction” and “oxidation”.
Here, reduction refers to a chemical reaction wherein a substance receives electrons, and oxidation refers to a chemical reaction wherein a substance loses electrons. As electrons are released or accepted in oxidation reduction reactions, oxidation and reduction currents flow by electron transfer.
The ORP (or redox potential) is the potential produced when electrons are released or accepted in an oxidation-reduction reaction, and can be used as a measure for the tendency of a substance to release or accept electrons. The ORP is determined by the number of electrons, configuration, and number of ligands of each substance and can be used as an indicator for identifying the substance.
The concentration of a substance in a solution can be determined by measuring oxidation current and reduction current in the solution with the use of the ORP measuring device, as mentioned above. Using the ORP measuring device, the substance in the solution can be identified and the oxidation-reduction reaction can be clarified, based on the ORP determined from the oxidation current and reduction current.
The conventional ORP measuring device for measuring the concentration of a substance in a solution to identify the substance includes an element that carries measurement electrodes for measuring the oxidation current and reduction current of the solution, and an element that carries a processing circuit for processing the obtained oxidation and reduction current signals. These elements are separate, and the measurement electrodes and the processing circuit are connected to each other via wiring.
Generally, the measurement electrodes of the ORP measuring device are made up of a working electrode, a counter electrode, and a reference electrode. The oxidation and reduction currents flow between the working electrode and the counter electrode. The oxidation and reduction current signals are processed by the processing circuit to determine the concentration of the substance in the solution, and the substance is thus specified.
ORP measuring devices are used for research and applications of various chemical reactions including bioreactions in a variety of fields such as agricultural, medical, and environmental fields.